The present invention relates to a hollow golf club head.
Among the recent technology advancements for hollow driver-type golf club heads, two areas of technology advancement are noteworthy. The first is the size of the head, which became larger with a cavity design where the weight is located on the outer surfaces (outer perimeter) of the cavity. The moment of inertia of the golf club head is increased with this head geometry along with the presence of weights on the perimeter. For a golfer, an increased moment of inertia makes a golf shot which misses the sweet spot generally travel toward the intended target by countering slicing and hooking ball trajectories. Therefore, a shot that misses the xe2x80x9csweet spotxe2x80x9d is more forgiving in terms of accuracy with a larger club head. The term sweet spot is well recognized by those skilled in the pertinent art.
The second technology advancement concerns the development of metal striking faces composed of titanium or steel. The metal striking face of a modern driver-type golf club head has been specifically constructed to achieve an efficient energy transfer from the metal striking face to the golf ball to achieve greater distance. A driver-type golf club head design based on a sweet spot with increased thickness, and a thinner region around the sweet spot has been accepted by club manufacturers as generating a higher C.O.R. (Coefficient Of Restitution). The C.O.R. is generally a measure of the ratio of the velocity out to velocity in. The United States Golf Association (USGA) regulates the C.O.R. using a test defined at www.usga.com, which involves a specific golf ball fired at a detached golf club head mounted on a pedestal.
The technology advancements to obtain maximum distance from a driver-type golf club head is well documented and widely advertised by many club manufacturers, such as Callaway Golf. In order to achieve longer distance from a driver, manufacturers have designed drivers with CORs at the limit of 0.83 in order to conform to the rule set forth by USGA in the USGA Procedure for Measuring the Velocity Ratio of a Club Head for Conformance to Rule 4-1e, Appendix II. Revision I, Aug. 4, 1998 and Revision 0, Jul. 6, 1998.
Some have recognized the problem and disclosed possible solutions.
An example of a large volume composite club head is Kodama et al., U.S. Pat. No. 6,354,963 for a golf club head. Kodama discloses a hollow golf club head made from a fiber reinforced epoxy resin that includes carbon fiber. It provides for a longer flight distance, a larger sweet spot and reduced veering in the flight path than a conventional golf club head.
Another example of a composite golf club head is Murphy et al., U.S. Pat. No. 6,248,025 for composite golf club head and method of manufacturing. The golf club head with a striking plate is composed of a composite material. The golf club head body is also composed of a composite material, and a weight strip is placed within a ribbon of the body.
Yet another example of a composite club head is Helmstetter et al., U.S. patent application Ser. No. 20020006836 for high moment of inertia composite golf club head. Helmstetter discloses golf club head of a high moment of inertia composed of a composite material and having a weight strip in a ribbon section.
The above prior art includes a composite club head with carbon fiber material including the striking face. The face composite plate is made relatively thick compared to the metal counterpart. Kodama et al., U.S. Pat. No. 6,354,963, discloses the face with a minimum thickness of 4 mm while Murphy et al., U.S. Pat. No. 6,248,025 discloses the striking plate having a thickness in the range of 0.110 inch (2.8 mm) to 0.155 inch (3.9 mm). A thicker plate is used with carbon fiber material because the composite has a relatively a low impact resistance and therefore a thin composite plate is not practically strong. However, a thicker composite becomes stiffer and the club face plate with a high thickness dimension does not deflect. On the other hand, the club head with a metal face with the thicker sweet spot with a thinner outer design deflects (and recovers) to give a higher C.O.R.
An example of a metal striking face is Lo, U.S. Pat. No. 5,328,176, for a composite golf head. Lo discloses a composite golf head having a front face of a metal reinforcing plate that has an upper extension fixed to a first part of the top portion. The metal reinforcing plate has a lower extension fixed to and wrapping around the bottom face and the rear face and extending to a second part of the top face.
Another example of a metal striking face is Cheng, et al., U.S. patent application Ser. No. 20010049310, for golf club head and a method for manufacturing the same. Cheng discloses a golf club head having a metal base, face and tubular neck and a carbon-fiber cover.
Yet, another example is Cackett and et al., U.S. patent application Ser. No. 20010055995, for a multiple material golf club head. Cackett discloses a golf club having a club head with a face component and an aft body. The face component, composed of a metal material, has a striking plate portion and a return portion. The aft-body is composed of a crown portion, a sole portion and optionally a ribbon section. The aft-body is composed of a non-metal material such as a composite material or a thermoplastic material.
The above prior art includes a composite club head with a metal face extended to the top and the bottom portion, U.S. Pat. No. 5,328,176, and a metal face that extends to the metal base, U.S. patent application Ser. No. 20010049310, and a metal face component having a return portion, U.S. patent application Ser. No. 20010055995.
The present invention provides a large volume composite golf club head having a metal striking insert molded within the front face wall of the club head body. One objective of the invention is accomplished by using a relatively smaller amount of metal material portion and a relatively larger amount of composite material to construct a golf club. The ratio of the composite material to the metal material is high.
One aspect of the present invention is the strength and durability of the attachment of the striking metal insert to the composite bead body by using a composite sandwiched structure. The edges of the striking metal insert extend outwardly and laterally to the general curvature of the outer surface of the golf club head. The edges of the striking metal insert are encapsulated by the composite layers to form the sandwich structure. This sandwich structure enables the present invention to dissipate the impact to the sandwiched structure and the rest of the composite body when the striking metal insert hits a golf ball.
The Present Invention is a larger volume club head with a higher moment of inertia. The moment of inertia of the golf club head is increased when the weight is located at the outer surface of the hollow club head. Heavier weight positioned farther from the center of gravity of the golf club head provides for a higher moment of inertia
A larger volume club head that results from the present invention gives a higher moment of inertia. The moment of inertia is increased when the weight is located at the outer surface of the hollow club head. The farther and the heavier weight is, the higher the moment of inertia is.
Yet another aspect of the present invention is a golf club head that efficiently dampens the shock on the metal striking insert. The composite sandwiched structure, with the edges extending outwardly and laterally from the striking insert and located right behind the striking metal insert, dampens the shock during impact with a golf ball. Furthermore, encapsulating the edges with a large amount of carbon fiber composite dampens the shock in a unique and effective way. For an average golfer who sometimes misses the xe2x80x9csweet spotxe2x80x9d of the golf club, the shock can produce an unpleasant feeling, and injure a golfer""s elbow.
Yet another aspect of this invention is a golf club head having a metal striking insert with edges of the insert extending outwardly and laterally from the striking insert and having grooves and/or holes. These grooves or holes are filled with composite material during molding, and the bonding between the edges and the composite body is made stronger due to the filling of the grooves or holes with composite material.
In one preferred embodiment, the present invention provides a golf club head including a metal striking insert and a hollow club head body composed of a carbon fiber composite material. The hollow club head body includes a front face wall with an open portion within the perimeter of the front face wall. The metal striking insert is molded within at least a portion of the perimeter of the front face wall.
Other objects, features and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings.